Correct behaviour during thunderstorms: Potz Blitz!

What to do during a thunderstorm? Here are the most important rules of behaviour:

1. Keep an eye on the weatherCheck the weather forecast before your tour. If thunderstorms are forecast, plan your route accordingly. What applies to surfers also applies to mountain bikers when there is a risk of thunderstorms: "If in doubt, don't go out!" If there is a risk of thunderstorms, stay at home. This is particularly difficult in the Bavarian Alps, where thunderstorms occur almost daily in summer.
2. Avoid high altitudes: If there are signs of a thunderstorm, the motto is: get off the summits, ridges and crests as quickly as possible. These high points are particularly dangerous during thunderstorms.
3. Seek shelterTake shelter in a building or car if possible. If this is not possible, look for a hollow or a low-lying area away from exposed areas.
4. Avoid lightning conductorsAvoid metal objects (including the bike), isolated trees and tall structures as they can attract lightning.
5. Keep your distanceKeep a safe distance from rocks or other people. At least 3 metres is recommended to prevent lateral overvoltage caused by lightning.
6. Get off your bike: Get off your bike and park it several metres away. Squat down with your feet together and wrap your arms around your legs to minimise the contact area with the ground.
7. Make a low profileMake yourself as small as possible and only touch the floor with your feet. Avoid lying down.
8. Keep away from metal equipmentThis applies more to climbers (ice axe, safety hooks).
9. Wait until the storm has passedWait at least 30 minutes after the last thunderclap before resuming your journey.

Correctly assess the risk of thunderstorms in the mountains

Thunderstorms in the mountains can quickly become a life-threatening danger for hikers, bikers and mountaineers. Even if the weather forecast does not report any rain for the day, localised thunderstorms can develop, especially in summer. Experts therefore advise you to keep a close eye on the sky at all times during your tour. The warning signs of an approaching storm include towering clouds that seem to push against an invisible boundary at the top. Dark clouds, weather lights, individual flashes of lightning or rumbling thunder in the distance as well as strong winds and rain are also signs of an approaching storm. In such cases, you should abandon your hike as quickly as possible and seek shelter. Tip: Install the app of the German weather service, it is quite accurate.

The right tour planning as the basis for safety

To minimise the risk of thunderstorms, experts recommend careful tour planning. Especially in the summer months, when the risk of thunderstorms is at its highest, you should set off as early as possible in the morning. The aim should be to reach the starting point in the valley or the nearest mountain hut in the early afternoon. If the weather is uncertain, shorter tours with alternative routes are preferable. Along the route, safe shelter options such as inns or mountain huts should be known. In many hiking areas, hiking buses also offer the option of shortening individual stages or the return journey if necessary. In addition to using weather apps, it is also advisable to listen to the local weather report on the radio or ask locals for their opinion.

Choose the right shelter during thunderstorms

If a thunderstorm breaks out, it is crucial to find a suitable shelter quickly. Buildings with a lightning protection system or a closed car offer the best protection. Special shelters with a lightning protection system and bus stops with metal supports and a metal roof can also offer a certain degree of protection from lightning. Open shelters or shelters without lightning conductors, on the other hand, are not safe havens. Experts also warn against seeking shelter under trees. If a tree is struck by lightning, it can explode and scatter parts over long distances. There is therefore just as much danger to life in the forest during thunderstorms as in open areas. The saying: "Avoid oaks, look for beeches" does not refer to the type of tree, but is aimed at avoiding free-standing trees (often oaks) and instead seeking shelter in homogeneous woodland (beeches) - but experts advise against both.

Correct behaviour in open terrain

If you find yourself in open terrain during a thunderstorm, you should leave exposed areas such as ridges or via ferratas immediately. Instead, experts recommend travelling close to a rock face if possible. The probability of a direct lightning strike is lower there. However, you should keep at least one metre away to avoid being struck by lightning. You should also keep your legs close together to reduce the risk of so-called step voltage. In a group, people should position themselves at a distance of 3 to 5 metres from each other. Contrary to previous recommendations, experts now advise against crouching down, as this gives a false sense of security.

Avoid bodies of water and metal objects

You should always stay away from bodies of water during thunderstorms. Lightning can strike lakes or rivers and carry the current over long distances in the water. Swimming or being in boats is therefore life-threatening when there is a risk of lightning. It is particularly risky on a sailing boat due to the high mast. All metal objects such as mobile phones, bicycles or walking sticks should also be kept at a distance during thunderstorms. Although these do not attract lightning, they can pass on the current and cause severe burns if struck nearby.

The danger of crotch tension

An often underestimated risk during thunderstorms is the so-called step voltage. When lightning strikes the ground, the electrical voltage spreads in a circle around the point of impact. The greater the distance between your feet, the greater the potential difference and therefore the greater the risk of current flowing through your body. For this reason, you should place your feet as close together as possible during thunderstorms outdoors. Under no circumstances should you lie flat on the ground, as your body would then absorb more voltage from the ground. Instead, experts recommend sitting on an insulating surface such as a sleeping mat or rucksack and keeping your feet close together.

Tech-Facts "Current flow":

The current flows due to a voltage difference because electric charges move from an area of higher voltage to an area of lower voltage in order to achieve equilibrium. This movement of charges is what we call electric current.

In the event of a lightning strike, the point of impact generates a considerable voltage difference in the ground. This voltage difference usually decreases with increasing distance from the point of strike. If your feet are far apart, they may touch two points on the earth's surface with different voltage levels, which could cause a current to flow through your body.

However, when the feet are placed together, they basically touch almost the same point on the earth's surface with voltage levels that are closer together or even identical. This greatly reduces the potential for significant current flow through the body. This measure can reduce the risk of being injured by the so-called step voltage effect, which occurs when a person's feet touch two points on the earth with a voltage difference between them.

After the thunderstorm: when is the danger over?

Even if the thunderstorm seems to have passed, caution is advised. Experts advise not going outside again until 30 minutes after the last clap of thunder. The sound of thunder travels at a speed of around 300 metres per second. If you can count to 3 between lightning and thunder, the thunderstorm is still about one kilometre away. A distance of at least 10 kilometres is considered safe, which corresponds to a counting time of 30 seconds between lightning and thunder. As the weather situation can change quickly, it is advisable to remain particularly alert after a thunderstorm and to cancel the tour if necessary.

First aid for lightning strikes

Despite all precautionary measures, a lightning strike can occur in rare cases. Contrary to popular belief, around 80 to 90 per cent of lightning victims survive the incident. Quick action is crucial. In most cases, cardiac arrest occurs, which must be treated with immediate resuscitation measures. Experts recommend hitting the victim firmly on the chest to get the heart beating again. Unlike a heart attack, the heart has only been stopped briefly by the electrical activity and can often be easily resuscitated. In addition to cardiac arrest, indirect injuries such as falls or falling branches can also be life-threatening. Although burns do occur, they are usually less dramatic than other electrical injuries.

Risk groups and preventive measures

People who frequently spend time outdoors for work or leisure are particularly at risk. These include farmers, foresters and outdoor sports enthusiasts such as golfers, footballers, climbers, hikers, sailors and mountain bikers. It is particularly important for these groups to familiarise themselves with the dangers of thunderstorms and the correct behaviour.

Knowledge to show off: Weather lightning vs lightning strike

Lightning and weather lightning are both atmospheric phenomena associated with thunderstorms, but differ in their appearance and perception:

1. Lightning strikeA lightning strike is an electrical discharge within a cloud, between clouds or between a cloud and the ground.
   It is accompanied by a bright flash of light followed by thunder.
   Lightning strikes are usually visible and audible in the vicinity of a thunderstorm.
   They pose a potential danger as they can release high levels of electrical energy.
   
2. Weather lightWeather lighting refers to the flashing of distant lightning whose thunder cannot be heard.
   It occurs when the lightning of a distant thunderstorm lights up the clouds or the sky, but the sound of the thunder is not audible due to the great distance.
   Weather lightning is often observed on clear nights and indicates a distant thunderstorm. In contrast to direct lightning strikes, weather flashes are not directly dangerous as they occur far away from the observation point.
   
3. Thunder and lightning? Actually wrong, because both are basically the same thing. The explosive noise comes from the lightning channel. There, the air first expands and is then compressed again. Only the distance and the sound cause lightning and thunder to separate because of the slow speed of sound. In an immediate thunderstorm, lightning = thunder.
   

Lightning strike statistics

• In a typical summer month, around 200,000 lightning bolts discharge over Germany
• Survival rate for lightning strikes: 80-90%
• Main cause of death: cardiac arrest

Safety distances

• Minimum safety distance from thunderstorms: 10 kilometres
• Corresponding counting time between lightning and thunder: 30 seconds
• Recommended waiting time after last thunder: 30 minutes

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